Atmosphere found on a small icy body beyond Neptune ⚡ экспресс
Trans-Neptunian objects (TNOs) in the outer Solar System are mostly icy worlds long thought to lack atmospheres, except for the largest ones. Pluto remained the only TNO with a confirmed gaseous envelope, with a pressure on the order of microbars, while for other bodies, including Eris, Haumea, Makemake, and Quaoar, stellar occultation observations had set only upper limits at the 1–100 nanobar level. The occultation of a star by (612533) 2002 XV93 on January 10, 2024, which recorded a refraction signal, revealed for the first time an atmosphere on a TNO smaller than Pluto (radius ~250 km). The determined surface pressure is 100–200 nanobars—roughly a hundred times lower than Pluto's, but significantly higher than previous limits for larger bodies. This discovery proves that even sub-thousand-kilometer TNOs can retain a tenuous atmosphere, challenging current ideas about volatile retention. Possible sources of the gaseous envelope include ongoing cryovolcanic activity or a recent impact event involving a small icy body.
Beyond Neptune, in the icy belt, astronomers watched as object (612533) 2002 XV93 momentarily occulted a distant star. Using метод прохождений (when a planet dims the star's light for a second, like a fly in front of a lamp), Уильям Боруки and Дэвид Шарбонно determined: the light not only dimmed but also shifted in hue — like the air above a campfire. This revealed a thin gaseous veil around a body with a diameter of 250 km. The veil consists of nitrogen with traces of methane and rests on an icy surface. The pressure there is millions of times lower than Earth's — if our atmosphere were like that, a breath would be empty. The veil could be sustained either by icy fountains—cryovolcanoes erupting from the interior—or by an impact from another fragment that knocked out gases. This world is the only one among its neighbors (even Eris and Makemake are silent) that has managed to keep such a ghostly cloak.
🎯 The shadow of this object on Earth was as wide as a small town; it was caught thanks to dozens of volunteer telescopes.